Grilled pesto chicken sandwiches taste great, I like to get them at the local deli's and places like Panera Bread. It's a pretty basic sandwich, it comes with a grilled chicken breast, a thick slice of tomato, sometimes a red onion, always a thick slice of mozzarella. I've had them with lettuce before too.
The bread is important, it either has to be a french baguette or fresh ciabatt. It has to have that soft chewy type texture because the grilled chicken combined with motz and tomato is opposite. Sometimes that's why I prefer lettuce and a little red onion to give it a more crisp somewhat crunchy texture. Making myself hungry.